U.S. patent application number 11/703876 was filed with the patent office on 2007-12-27 for method and apparatus to perform reactive jamming while simultaneously avoiding friendly pseudo-random frequency hopping communications.
Invention is credited to Lars Karlsson.
Application Number | 20070297489 11/703876 |
Document ID | / |
Family ID | 38873541 |
Filed Date | 2007-12-27 |
United States Patent
Application |
20070297489 |
Kind Code |
A1 |
Karlsson; Lars |
December 27, 2007 |
Method and apparatus to perform reactive jamming while
simultaneously avoiding friendly pseudo-random frequency hopping
communications
Abstract
Method and Apparatus to Perform Reactive Jamming While
Simultaneously Avoiding Friendly Pseudo-Random Frequency Hopping
Communications is disclosed. The system provides an enhancement to
surgical reactive jammers that combines near-real-time jamming
capability with the additional feature of allowing tactical
communications. The jammer includes a synchronization subsystem
that synchronizes jammer lockout frequencies with those frequencies
being hopped to by units that are members of a friendly
communications network. The synchronization subsystem is
coordinated with, and therefore tied to the time-synchronized
cryptography of the friendly communications net. As a result, the
jammer will be aware, on a real-time basis, which frequency the
friendly communications network will next be hopping to. The
jammer's awareness of these future frequencies will allow those
frequencies to be "locked out" of the jammer's transmission band
dynamically.
Inventors: |
Karlsson; Lars; (Santa
Clara, CA) |
Correspondence
Address: |
Karl M. Steins;Steins & Associates
Suite 120
2333 Camino del Rio South
San Diego
CA
92108
US
|
Family ID: |
38873541 |
Appl. No.: |
11/703876 |
Filed: |
February 7, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11480706 |
Jul 3, 2006 |
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11703876 |
Feb 7, 2007 |
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10912976 |
Aug 6, 2004 |
7126979 |
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11703876 |
Feb 7, 2007 |
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60765824 |
Feb 7, 2006 |
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Current U.S.
Class: |
375/134 ;
375/E1.033; 375/E1.036 |
Current CPC
Class: |
H04B 1/715 20130101;
H04K 3/28 20130101; H04K 3/45 20130101; H04K 3/42 20130101 |
Class at
Publication: |
375/134 ;
375/E01.033 |
International
Class: |
H04B 1/713 20060101
H04B001/713 |
Claims
1. An electronic signal jamming system having synchronized,
frequency-hopping transmission lockouts, comprising: antennae means
for receiving incident RF signals; an RF splitter for splitting
said incident RF signals into a jamming system input data stream
and a synchronizing input data stream; a dynamic synchronization
subsystem, comprising: a synchronization receive module for
receiving said synchronizing input data stream and converting it to
a time correction data stream if said synchronizing system input
data stream is on one of a group of predetermined frequencies; a
random number generator (RNG) means for generating
time-synchronized random numbers, said RNG means responsive to said
time correction data stream; and a bin lockout command generator
(BLCG) means for generating floating lockout frequency bin
commands, said BLCG means responsive to said RNG means; and an
electronic signal jamming system, comprising: a wideband signal
collection front end receiving said jamming system input data
stream; and a signal evaluation logic module responsive to said
floating lockout frequency bin commands; and an internal
transmitter also responsive to said signal evaluation logic module
for transmitting a jamming signal on a frequency of interest
determined by said signal evaluation logic module.
2. The system of claim 1, wherein said synchronization receive
module further comprises: a narrowband tuner for converting said
synchronizing input data stream into an analog IF data stream if
said synchronizing input data stream is on a frequency that is one
of said group of said predetermined frequencies; and synchronizing
pulse processor means for converting said analog IF data stream
into a time correction data stream.
3. The system of claim 2, wherein said synchronization receive
module further comprises: time signal receiver means for receiving
a master time signal; an synchronizing internal clock responsive to
said master time signal and said time correction data stream to
generate a synchronized time data stream; and whereby said RNG
means said responsiveness comprises said RNG means being responsive
to said synchronized time data stream.
4. The system of claim 3, wherein said RNG means is further
responsive to a preloaded seed value.
5. The system of claim 4, wherein said BLCG means is further
responsive to a preloaded table of hop data, whereby said lockout
frequency bin commands are responsive to said time-synchronized
random numbers and said hop data.
6. The system of claim 5, wherein said electronic signal jamming
system further comprises: said wideband signal collection front end
having a wideband receiver for receiving RF signals across a broad
spectrum, a digitizer for creating a continuous stream of digitized
data representing said received RF signals, and a digital data
conversion means for converting said digitized data into FFT
frequency bins; and said signal evaluation logic module having a
comparing means for comparing each said frequency bin to
configurable preset lockout frequency bins in addition to frequency
bins identified within said floating lockout frequency bin
commands, a peak detection means for evaluating and calculating the
amplitude value for each bin by using a configurable number of data
point samples for each of those bins, a windowing means for
evaluating and calculating the amplitude value for each bin by
using a configurable number of data point samples for each of those
bins, and a priority selection means for evaluating the
prioritization of jammer signal targets based upon configurable
settings; and an internal transmitter also responsive to said
comparing, peak detection, windowing, and priority logic for
transmitting a jamming signal on a frequency of interest.
7. The system of claim 6, wherein said digital data conversion
means comprises means for converting said digitized data from a
time domain to a frequency domain.
8. The system of claim 7, wherein said digital data conversion
means comprises means for converting said frequency domain
converted data from separate real and imaginary components to
normalized amplitude data.
9. The system of claim 8, wherein said normalized amplitude data is
categorized by frequency bins.
10. The system of claim 9, wherein said comparing means comprises
comparing data in said frequency bins to both present and floating
frequency lockouts.
11. The system of claim 10, further comprising peak detection means
for evaluating the amplitude of said frequency bins.
12. The system of claim 11, wherein said windowing means for
evaluating each bin to be within configurable amplitude bound
limits.
13. The system of claim 12, further comprising means for comparing
said amplitude-evaluated signal to a pre-established signal
priority list.
14. The system of claim 13, wherein said signal priority logic
means further compares said amplitude-evaluated signal to a
real-time priority request.
15. A method for synchronizing jamming RF signal transmissions with
third party RF communications, comprising the steps of: detecting
an analog RF signal transmission; splitting said analog RF signal
transmission into a jamming system RF (JSRF) signal and a
synchronization subsystem RF (SSRF) signal; generating a floating
lockout frequency bins responsive to said SSRF signal; executing a
jamming method, said jamming method comprising the steps of:
digitizing said detected JSRF signal; converting said digitized
JSRF signal into frequency bins; comparing said frequency bins to
said floating lockout frequency bins; evaluating and calculating
the amplitude value for each said bin by using a configurable
number of data point samples for each of those bins; evaluating the
prioritization of jammer signal targets based upon configurable
settings; triggering said start of the conversion of said digitized
signals into said frequency bins; triggering the end of the
conversion of said digitized signals into said frequency bins;
triggering the release of frequency bin information at the correct
time; triggering of the external power amplifier at the correct
time to prepare for jammer signals; and automatic programming of a
digital signal generator to generate a jamming signal, said signal
generator triggering responsive to said comparing.
16. The method of claim 15, wherein said jamming method further
comprises a lockout step prior to said comparing step, said lockout
step comprising comparing said converted digitized signals to a
dynamic list of lockout frequency bins.
17. The method of claim 16, wherein said jamming method further
comprises a signal threshold-comparing step prior to said comparing
step, comprising comparing said frequency bins to signal threshold
settings.
18. The method of claim 17, wherein digital transmitter triggering
step is responsive to said signal threshold-comparing step.
Description
[0001] This application is a continuation in part of application
Ser. No. 11/480,706, filed Jul. 3, 2006, and Ser. No. 10/912,976,
filed Aug. 6, 2004, now U.S. Pat. No. 7,126,979. The
below-identified Provisional Application was copending with
application Ser. No. 10/912,976.
[0002] This application is filed within one year of, and claims
priority to Provisional Application Ser. No. 60/765,824, filed Feb.
7, 2006.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] This invention relates generally to electronic warfare and
communications systems and, more specifically, to a Method and
Apparatus to Perform Reactive Jamming While Simultaneously Avoiding
Friendly Pseudo-Random Frequency Hopping Communications.
[0005] 2. Description of Related Art
[0006] This provisional patent application relates to an enhanced
electronic warfare reactive jammer capability to deny enemy
communications while simultaneously avoiding (i.e. not jamming)
friendly pseudo-random frequency hopping communications that are
operating in the same vicinity.
[0007] It is worthy to note that this patent application is
marginally similar, to a another patent application Ser. No.
11/480,706, entitled "Method and Apparatus to Perform Surgical
Reactive Jamming While Maintaining Simultaneous Tactical
Communications", also filed by this author. But that previous
filing has sharp differences and distinctions from this present
filing. The previous filing was for a reactive jammer that could
itself also act as a secure communications device. The present
filing is for a reactive jammer that can operate alongside separate
3rd party co-located military grade communications radios. The
invention described herein outlines a unique technique to protect
the pseudo-random frequency hopping signals of friendly 3rd party
radios, which normally would have been jammed by a fast reactive
jammer.
[0008] This capability is essential for mobile reactive jammer
units in the field. Such field units typically need to maintain
their own secure voice communications ("comms") with other mobile
units, or higher eschelon commands, for tactical orders, safety
considerations, and battlefield coordination. The problem today for
present day units is that while performing their respective jamming
missions, it precludes them from using their own tactical
communications links due to the fact that the very nature of the
reactive jammer will prevent their own tactical comms equipment to
make a connection. Thus the operating personnel must make a choice
between using one or the other at any given time.
[0009] The invention described in this provisional patent
application solves that issue and provides a unique capability to
perform both surgical reactive jamming while simultaneously
allowing tactical communications to proceed from separate 3rd party
military radios. This invention is therefore vital to the interests
of United States national security as it provides a valuable
Electronic Warfare capability, as it greatly reduces electronic
fratricide of our own communications nets.
[0010] The jammer device described by patent application Ser. No.
10/912,976 is sometimes referred to in the Electronic Warfare
industry as a "wideband reactive jammer", "surgical follower
jammer," or a "surgical reactive jammer" because it has the ability
to quickly find enemy signals and then apply energy exactly on
target so as to jam those enemy communication signals. This has
greatest application against modem military radios that are known
as "frequency hoppers". Unfortunately, the very same radio
technologies are used for friendly communications. So this
invention describes how to jam enemy pseudo-random frequency
hopping signals, while simultaneously ignoring the friendly
pseudo-random frequency hopping signals (from 3rd party
radios).
[0011] What is needed therefore in order to feasibly detect and jam
modern fast transmissions while at the same time maintain tactical
communications with friendly 3rd party pseudo-random frequency
hopping radios is a system that not only has: 1) The abilities
stated in the aforementioned previous patent application Ser. No.
10/912,976, but also 2) The ability to accept and process the same
frequency hopping program data of the 3rd party radios in question,
and also 3) The ability to be precisely synchronized with all other
friendly 3rd party radios in the field in both timing and
communications hop sets, and finally 4) The ability to have a
floating lockout (i.e. selectively not jam) all the frequency
hopping signals from the friendly 3rd party radios.
SUMMARY OF THE INVENTION
[0012] In light of the aforementioned problems associated with the
prior systems and method, it is an object of the present invention
to provide a Method and Apparatus to Perform Reactive Jamming While
Simultaneously Avoiding Friendly Pseudo-Random Frequency Hopping
Communications. It is an object that the system provide an
enhancement to surgical reactive jammers that combines
near-real-time jamming capability with the additional feature of
allowing friendly tactical communications. The jammer should
include a system that synchronizes jammer lockout frequencies with
those frequencies being hopped to by units that are members of a
friendly communications network. The synchronization system should
be coordinated with the time-synchronized cryptography of the
friendly communications net. The jammer should, therefore, be
aware, on a real-time basis, which frequency the friendly
communications network will next be hopping to. The jammer's
awareness of these future frequencies will allow those frequencies
to be "locked out" of the jammer's transmission band
dynamically.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The objects and features of the present invention, which are
believed to be novel, are set forth with particularity in the
appended claims. The present invention, both as to its organization
and manner of operation, together with further objects and
advantages, may best be understood by reference to the following
description, taken in connection with the accompanying drawings, of
which:
[0014] FIG. 1 is a depiction of the Surgical Reactive Jammer System
of application Ser. No. 10/912,976; and
[0015] FIG. 2 is a depiction of the System of FIG. 1 further
including the Synchronization Subsystem of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] The following description is provided to enable any person
skilled in the art to make and use the invention and sets forth the
best modes contemplated by the inventor of carrying out his
invention. Various modifications, however, will remain readily
apparent to those skilled in the art, since the generic principles
of the present invention have been defined herein specifically to
provide a Method and Apparatus to Perform Reactive Jamming While
Simultaneously Avoiding Friendly Pseudo-Random Frequency Hopping
Communications.
[0017] The discussion of the present invention will first commence
by review of FIG. 1, FIG. 1 shows the system diagram of a prior art
surgical reactive jammer as described by patent application Ser.
No. 10/912,976. As mentioned, the present invention is an extension
and an augmentation to a previously filed U.S. patent application
Ser. No. 10/912,976: "System and Method to Autonomously and
Selectively Jam Frequency Hopping Signals in Near Real-Time." The
disclosure of this parent application will be referenced
continually throughout the instant description, and is therefore
incorporated herein by reference.
[0018] This jammer uses a device that has a wideband front-end
which can digitally processes the entire intermediate frequency
(IF) output at once. Thus all the signal information contained
within the bandwidth of the IF filter can be analyzed instantly.
The resulting IF output may contain one or many short duration
communication signals.
[0019] The next section contains the selection logic by which it is
automatically determined whether or not the received signal should
be jammed. The cycle generator section regulates the user
configurable System timing. The final section of the surgical
reactive jammer executes the jamming frequency generation and
output, which must also occur extremely quickly. All of these
processes occur in near real time.
[0020] The Wideband Downconverter, A/D Converter, FFT, Lockouts,
Peak Detection Algorithm, and Signal Evaluation Logic sections of
the prior art jammer design are not changed in the present
invention. Thus for simplicity in drawing the following FIG. 2,
those module sections are grouped together and labeled "Jammer
Block".
[0021] FIG. 2 outlines a flow block diagram of the invention. An RF
splitter is used to split the incoming signals into two fully
independent processing paths (identified in application Ser. No.
11/480,706 as 400A and 400B). As an alternative embodiment of the
invention, separate antennas could also be used. The first path is
through the Jammer Block which performs all the surgical reactive
jamming functions. In this path, the signals go through the normal
processing to determine whether or not various detected signals
should be jammed.
[0022] The second path is independent and uses it's own narrowband
tuner to specifically pick up the synchronization channels (or
over-the-air programming commands) of the 3rd party radios. These
sync channels typically are used to broadcast timing information to
the rest of the radio net from the master radio, so that all slave
radios will be aligned with the clock of the master. The sync
information is then fed to a processor and the results are fed into
an internal clock module. This internal clock is disciplined by a
GPS Time Receiver. The synchronized time is then fed to a
conventional pseudo-random number generator which, when programmed
with the same "hop-set" and "seed" values, will send out a
pseudo-random number which corresponds to a specific bin number
whereby the invention will know not to jam any information
appearing on that particular bin frequency. The method of using FFT
bins is unique and is the heart of the efficiency of this approach
and invention. All of these functions above are described in more
detail in the following Operation section of this patent
application.
DIAGRAM REFERENCE NUMERALS
[0023] 10 PIN Diode Attenuator Switch [0024] 12 Wideband
Downconverter and Filters [0025] 14 Analog-to-Digital Converter
(A/D) [0026] 16 Fast Fourier Transformations (FFT's) [0027] 18
Lockout Logic [0028] 20 Peak Detection Algorithm [0029] 22 Signal
Evaluation Algorithm [0030] 24 Memory and Priority Select Logic
[0031] 26 Direct Digital Synthesizer (DDS) Signal Generators [0032]
28 Upconverter Oscillator [0033] 30 Cycle Generator [0034] 32 Mixer
[0035] 34 High Power Amplifier (PA) and Output Filter [0036] 100 RF
Splitter [0037] 102 Narrowband Tuner [0038] 104 Analog IF Signals
[0039] 106 Sync Pulse Processor [0040] 108 Time Correction Data
[0041] 110 GPS Time Receiver [0042] 112 Time Data [0043] 114
Internal Clock [0044] 116 Synchronized Time Data with Master Radio
[0045] 118 PRNG Seed [0046] 120 Pseudo-Random Number Generator
(PRNG) [0047] 122 Pseudo-Random Number Output [0048] 124 Bin Hop
Set Table Load [0049] 126 Bin Hop Set Lookup Table [0050] 128 Set
Floating Lockout Frequency Bin Command [0051] 200 Jammer Block
[0052] 300 Invention Operation
[0053] The operation of the invention 300 is described here in this
section. It is assumed that the reader is already familiar with how
the reactive jammer technology works (minus the enhancement of this
invention) by reading the aforementioned patent application Ser.
No. 10/912,976. Most of the details regarding that prior art will
not be discussed here. Rather the discussion in this document will
focus on the invention 300 at hand which is an augmentation to the
prior art system. As before, a wideband digital reception technique
of the reactive jammer is used to instantaneously detect the
presence of enemy signal energy within large bands of RF spectrum.
Detection of signals occur on cyclical "look-through's" which are
short time periods whereby the jammer does not radiate so as to
allow the wideband front end tuner to have the sensitivity to pick
up any newly occurring signals. Once this period is complete the
jammer will emit energy once more until the next look-through
period. This "attack cycle" repeats itself indefinitely during
jamming operations. This element of the prior art is the same as
the invention 300. The difference arises out of additional
circuitry and software that synchronizes with the 3rd party
frequency hopping radios and then feeds specific information back
into the jammer decision tree which alters the (transmission)
firing solution.
[0054] To begin with, a short discussion on the nature of military
frequency hopping radios is required. It is assumed that the reader
is familiar with how standard military grade frequency hopping
radios work and are utilized in a network. But to summarize, most
frequency hopping radios require several data elements in order to
operate. The minimum requirements are the values of a frequency hop
set and a pseudo-random number generator (PRNG) Seed value. Some
radios, for example, also have additional data elements such as
transmission keys and net ID values. This patent will focus on the
generic version of a military grade frequency hopping radio.
Continuing forward, the hop set and PRNG Seed tell the radios in a
net when and where the next frequency setting to send information
will be. All data is broken up into small chunks and sent over
these pseudo-randomly distributed frequencies at definable times.
This principle is leveraged in this patent application as the
invention 300 will become another "node" in the 3rd party
communications net. It will be a slave to the master radio which
coordinates the timing of the frequency hops. In that way, the
invention 300 will "know" what the next hop is at all moments in
time. In so doing, it will calculate the corresponding frequency
bin number and use that bin number and a user settable number of
adjacent bin numbers as a lockout into the decision tree chain of
the jammer. Thus, a "floating lockout" will be established which
will protect the 3rd party communications net frequency hops at all
times. This is the general principle of operation of the invention
300.
[0055] Continuing forward with the invention 300 description,
signals come in through the receive antenna and are passed through
the PIN attenuator switch 10. This switch is only connected when a
look-through or talk-through period is active. The incoming signals
are split equally by an RF splitter 100.
[0056] One path of the incoming signals leads to jammer block 200,
which contains the sub-modules shown in FIG. 1. As mentioned, the
processing of this path is identical to that of the previous patent
application for the reactive jammer. Since there are no changes to
the jamming functionality, the processing details will not be
covered again in this document.
[0057] The second path of the incoming signals leads to new
additional hardware modules of this invention 300. The signal
proceeds to a narrowband tuner 102 which has the function of
listening for the synchronization/programming channels of the radio
net. Once detected, it will downconvert the signals to an
intermediate frequency for further processing. The resulting analog
IF signal 104 is then fed to circuitry which processes the
synchronization pulses 106 and creates a time correction. The time
correction data 108 is then fed to an internal clock 114.
[0058] The internal clock 114 is a standard counter which is used
to maintain the system's precise time. Since frequency hopping
radios in use today coordinate their information transfer according
to specific times, this circuitry plays a pivotal role in
synchronizing the invention 300 with the rest of the 3rd party
communications net. A GPS time receiver 110 is used to maintain
fidelity and to discipline the internal clock. The time corrections
108 and the time values 112 both feed into the internal clock 114
and the outputs are time values 116 that are synchronized with the
master radio in the net.
[0059] The synchronized time with the master 116 is then fed to the
PRNG 120. This PRNG is the exact same algorithm as the one that is
used in the 3rd party radios. For the invention 300 to work, there
are three things that must be same with the 3rd party radios in
question. The first is that the PRNG 120 needs to be identical
between both devices. The second is that both the invention 300 and
the 3rd party radios need to be programmed with the same PRNG Seed
118. And thirdly, the same hop set that is used in the radios must
be also input into the invention 300. Thus, with the synchronized
timing information 116 and the same PRNG Seed 118 when input into
the PRNF 120 will be the same pseudo-random number 122.
[0060] The final step is for the pseudo-random number 122 to be fed
into the bin hop set lookup table 126. Initially, the hop set of
the radios must be translated into a bin hop set load 124. This can
be done either offline or automatically by the invention 300. The
bin hop set load 124 is a frequency bin representation of the
analog frequency hop set of the radios. In the radio, the
pseudo-random number 122 identifies the exact frequency setting for
the radio to tune to in order to hear the next transmission hop. In
the invention 300, the pseudo-random number 122 identifies the
corresponding bin number where the hop frequency would be. The
result is the setting of a lockout on that particular bin 128. The
optimum way for the jammer to digitally process this information
fast enough is by operating by digital bin number values and not by
analog frequency values. This approach and technique is unique and
is the optimal way to perform the automated lockout process in the
reactive jammer system.
[0061] As the reader can see, the same frequency hopping pattern
that is used for the transmission of tactical communications with
the 3rd party radios is also used as a "floating lockout" situation
in the invention 300. Once the invention 300 is synchronized with
the friendly frequency hopping radios, it will "be aware" of the
next hop frequency in the net. It will then pass along that exact
frequency hop bin number to the invention's lockout circuitry 18
inside the jammer block 200 where the hop bin will be temporary
programmed into the protected frequencies table for a period of
time until the next hop occurs. So when the radio net moves to the
next hop, the invention 300 will be aware of that and will mark the
next hop bin accordingly as a protected frequency and release the
former bin. This creates a "floating lockout" bin situation.
[0062] In conclusion, this invention 300 is only able to process
all reactive jamming fast enough by using FFT bin numbers (as
described in the previous patent application that this patent
application builds upon). The virtue of the system is that it is
fast enough to handle frequency hopping radios. This invention now
deals with the real world issue of jamming friendly frequency
hopper radios.
[0063] The requirements for such compatibility are that the radios
and the invention have the same PRNG, have the same PRNG Seed
value, and have the same hop set data. Typically in real world
systems, the PRNG Seed value and the hop set data are encapsulated
in one single data load. This invention is flexible enough to
handle all such data loading protocols. An alternate embodiment of
the invention is to be able to load the critical information on the
fly, over the air. This can be done by utilizing the narrowband
tuner 102 to detect the wireless commands and process them
accordingly. In some radio systems, this process is known as the
Electronic Remote Fill feature. Through the unique methods and
techniques presented here, this invention will allow jamming
missions to continue while simultaneously allowing friendly 3rd
party tactical communications radios to not be jammed. This will
lead to significantly less electronic fratricide in the field and
offer the unique ability to jam while maintaining tactical
comms
[0064] Those skilled in the art will appreciate that various
adaptations and modifications of the just-described preferred
embodiment can be configured without departing from the scope and
spirit of the invention. Therefore, it is to be understood that,
within the scope of the appended claims, the invention may be
practiced other than as specifically described herein.
* * * * *